JP2007149691A - Polymer electrolyte membrane for fuel cell and fuel cell system including above - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polymer electrolyte membrane for a fuel cell and a fuel cell system including above. <P>SOLUTION: The polymer electrolyte membrane includes a polymer matrix bridged with hardening oligomer, and a proton conductive polymer of nano-size existing in the polymer matrix. Since the polymer electrolyte membrane for the fuel cell can be rapidly and easily manufactured, it has good productivity, and also, the fuel cell can be made to be thin, has good size stability and a hydrocarbon fuel blocking property, and good output density. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polymer electrolyte membrane for a fuel cell and a fuel cell system including the same, and more specifically, can increase mechanical strength and effectively cut off dimensional stability and fuel crossover. The present invention relates to a polymer electrolyte membrane for a fuel cell and a fuel cell system including the same.

  A fuel cell is a power generation system that directly converts the chemical reaction energy of hydrogen and oxygen contained in a hydrocarbon-based substance such as methanol, ethanol, and natural gas into electric energy. Such a fuel cell has an advantage that it can output a wide range of outputs by stacking a stack of unit cells as a clean energy source that can replace fossil energy. Since it shows 10 times the energy density, it is attracting attention as a compact and mobile power source for mobile use.

  Representative examples of the fuel cell include a polymer electrolyte fuel cell (PEMFC) and a direct oxidation fuel cell (Direct Oxidation Fuel Cell). When methanol is used as a fuel in the direct oxidation fuel cell, it is referred to as a direct methanol fuel cell (DMFC).

  The polymer electrolyte fuel cell has the advantages of high energy density and high output, but requires attention to handling of hydrogen gas, and in order to produce hydrogen as a fuel gas, methane and methanol In addition, there is a problem that ancillary equipment such as a fuel reformer for reforming natural gas or the like is required.

  On the other hand, the direct oxidation fuel cell has a lower energy density than the polymer electrolyte fuel cell, but the fuel is easy to handle and can be operated at room temperature because of its low operating temperature. There is an advantage that no reformer is required.

  In such a fuel cell system, a stack that substantially generates electricity includes several unit cells each including an electrode assembly (MEB) and a separator (also referred to as a bipolar plate). It has a structure in which thru tens are stacked. The electrode assembly is separated from a polymer electrolyte membrane containing a hydrogen ion conductive polymer by an anode electrode (referred to as “fuel electrode” or “oxidation electrode”) and a cathode electrode (referred to as “cathode” or “ It has a structure in which a reduction electrode is called.

  The principle of generating electricity in the fuel cell is that the fuel is supplied to the anode electrode of the fuel electrode and adsorbed on the catalyst of the anode electrode, and the fuel is oxidized to generate hydrogen ions and electrons. And reaches the cathode electrode of the oxidation electrode, and hydrogen ions pass through the polymer electrolyte membrane and are transmitted to the cathode electrode. An oxidant is supplied to the cathode electrode, and the oxidant, hydrogen ions, and electrons react on the catalyst of the cathode electrode to generate water while generating electricity.

  The polymer electrolyte membrane is an insulator that electrically separates the anode electrode and the cathode electrode. The polymer electrolyte membrane acts as a medium for transmitting hydrogen ions from the anode electrode to the cathode electrode during battery operation. Play the role of separation at the same time. Therefore, the polymer electrolyte membrane must have excellent electrochemical stability, high current density and low resistance loss, not only excellent separation of reactants during battery operation, A stack structure requires a certain level of mechanical properties and dimensional stability.

  As the polymer electrolyte membrane, from 1968 DuPont de Nemours, Inc., a hydrophobic polytetrafluoroethylene as a main chain and a hydrophilic sulfone group-containing functional group in the side chain. Since the development of a perfluorosulfonic acid-based cation exchange resin having a group (trade name: Nafion (registered trademark)), Nafion (registered trademark) has been widely used.

  The polytetrafluoroethylene main chain has the advantages of high oxygen solubility and far superiority to hydrocarbon polymer electrolyte membranes in terms of electrochemical stability and durability.

  The Nafion (registered trademark) polymer electrolyte membrane has a large oxygen solubility due to the polytetrafluoroethylene main chain, and is far superior to hydrocarbon polymer electrolyte membranes in terms of electrochemical stability and durability. Has advantages. However, when about 20% of the polymer weight of the Nafion (registered trademark) polymer electrolyte membrane is hydrated (that is, the sulfone group contained in the pendant group is hydrolyzed to the sulfonic acid from which it has been released). In order to exhibit conductivity with respect to hydrogen ions, the reaction gas used in the fuel cell must be saturated with water in order to hydrate the polymer electrolyte membrane. However, when the boiling point of water is 100 ° C. or higher, the moisture gradually dries, so the resistance increases and the performance of the battery rapidly decreases.

  In addition, Nafion (registered trademark) polymer electrolyte membranes are usually marketed in a thickness of 50 to 175 μm, and are manufactured in a film form by polymer melt extrusion or solvent casting. The At this time, increasing the thickness to improve dimensional stability and mechanical properties decreases the conductivity of the polymer electrolyte membrane, but decreases the thickness to reduce the resistance of the polymer electrolyte membrane. And mechanical properties deteriorate. In particular, in a methanol fuel cell, not only does liquid methanol fuel that does not react during cell operation pass through the polymer electrolyte membrane, resulting in fuel loss, but also methanol is oxidized at the cathode electrode and oxygen The reduction sites are reduced, the battery performance is lowered, and fuel loss is caused.

  In addition, Nafion (registered trademark) polymer electrolyte membrane is repeatedly swollen and shrunk in hydrophilic clusters finely phase-separated from the hydrophobic region depending on the temperature and the degree of hydration. Therefore, the dimensional stability is lowered in the thin film state, and the electrode and the electrolyte interface are deteriorated. Therefore, research to develop technology for producing polymer electrolyte membranes with improved mechanical properties, dimensional stability, fuel separation performance, and economy while maintaining hydrogen ion conductivity over a wide temperature range Is actively conducted worldwide.

  An object of the present invention is to provide a polymer electrolyte membrane for a fuel cell that can be produced economically with improved strength characteristics without reducing conductivity.

  Another object of the present invention is to provide a polymer electrolyte membrane for a fuel cell that exhibits excellent battery performance.

  Another object of the present invention is to provide a fuel cell system including the polymer electrolyte membrane.

  To achieve the above object, the present invention provides a polymer electrolyte membrane for a fuel cell comprising a polymer matrix in which a curable oligomer is crosslinked, and a nano-sized proton conducting polymer present in the polymer matrix. To do.

  The present invention also provides at least one electrode assembly and separator including an anode electrode and a cathode electrode positioned opposite to each other, and a polymer electrolyte membrane having the above-described configuration and positioned between the anode electrode and the cathode electrode. Including at least one electricity generating part for generating electricity through an electrochemical reaction between the fuel and the oxidant, a fuel supply part for supplying fuel to the electricity generating part, and an oxidant for supplying to the electricity generating part A fuel cell system including an oxidant supply unit is provided.

  The polymer electrolyte membrane for a fuel cell of the present invention can be manufactured quickly and easily, and is excellent in mass productivity. Further, the polymer electrolyte membrane can be thinned, and has excellent dimensional stability and hydrocarbon fuel barrier properties. Therefore, a fuel cell with excellent power density can be provided.

  Hereinafter, the present invention will be described in more detail.

  The present invention relates to a polymer electrolyte membrane for a fuel cell.

  Conventionally, perfluorosulfonate polymer electrolyte membranes that have been used as polymer electrolyte membranes increase the thickness to increase dimensional stability and mechanical stability, and the conductivity of the polymer electrolyte membranes decreases. If the thickness is decreased in order to reduce the resistance of the polymer electrolyte membrane, there is a problem that mechanical properties are deteriorated, and a hydrocarbon fuel such as methanol is crossed over to the cathode electrode side. was there.

In this context, US Pat. Nos. 5,547,551, 5,599,614, and 5,635,041 describe stretched porous polytetrafluoroethylene polymer electrolyte membranes (US Patent Nos. 3,953,566 and 3,962,153) are impregnated with a cation exchange polymer solution in a liquid state to produce a reinforced composite polymer electrolyte membrane (trade name: Gore-Select ^™ ). A method is disclosed. The polymer electrolyte membrane produced by the above method has a lower hydrogen ion conductivity (unit: Ω ⁻¹ cm ⁻¹ ) than that of the Nafion (registered trademark) polymer electrolyte membrane. Since the mechanical strength is maintained, a polymer thin film having a thickness of 25 μm can be produced, and the conductivity (unit: Ω ⁻¹ cm ⁻² ) of the composite polymer electrolyte membrane is relatively high in Nafion (registered trademark). It is known that it is superior to molecular electrolyte membranes. In particular, the membrane-electrode assembly (trade name: PRIMEA ^™ ) manufactured using the Gore-Select ^™ membrane shows the most excellent polymer electrolyte fuel cell performance at 100 ° C. or lower.

  However, since the polymer electrolyte membrane manufactured by the above method uses non-conductive polytetrafluoroethylene as a support, the conductivity of hydrogen ions is lower than that of pure Nafion (registered trademark) membrane. There are disadvantages.

  In addition, US Pat. No. 6,130,175 discloses a porous polytetrafluoroethylene film having a methyl ester precursor-form ion-exchange polymer resin having a perfluorocarboxyl functional group as a first ion-exchange material. One side surface is impregnated, and the other side surface is impregnated with an ion exchange polymer resin having a perfluorinated sulfonic functional group as a second ion exchange material, so that the first and second ion exchange materials are at least on the surface of the film. It discloses that nearby pores can be filled or occluded, thereby improving ionic conductivity and mechanical properties. U.S. Pat. No. 6,042,958 discloses a method of impregnating a perfluorinated sulfonic acid polymer after attaching a non-woven glass fiber substrate to both sides of a porous polytetrafluoroethylene film. .

  However, the composite polymer electrolyte membrane manufactured by the above-described method uses a non-conducting organic or inorganic support, so that a decrease in conductivity occurs and a decrease in conductivity is prevented. By reducing the thickness of the film in and out of 25 μm, the tear strength is relatively low. On the other hand, since a Nafion (registered trademark) resin must be impregnated on an expensive porous polytetrafluoroethylene support having a porosity of 80% or less, the cost burden is large. In addition, since the ion exchange resin must be repeatedly impregnated on the polytetrafluoroethylene film having low wettability, the manufacturing process is slow and discontinuous. In particular, since the separation capability of liquid methanol is low in the thin film state, when it is applied to a direct methanol fuel cell (DMFC) in which methanol is directly injected into the fuel electrode, the fuel loss is very large and the efficiency of the catalyst is reduced, so that the cell performance It has been pointed out as a disadvantage that it drops drastically.

  The composite electrolyte membrane manufactured by mixing various substances proposed to solve the conventional problems is reduced in the conductivity, and the polymer electrolyte membrane is used to prevent the decrease in conductivity. By reducing the thickness, the mechanical strength is lowered, the process is complicated, and the battery performance is lowered.

  In the present invention, as shown in FIG. 1, a dispersion liquid is produced by uniformly mixing a curable oligomer having a low molecular weight and in a liquid state at room temperature with a nano-sized proton conductive polymer (S1), A reaction initiator was added to this dispersion, and an electron beam or ultraviolet light was irradiated to induce a crosslinking reaction of the oligomer (S2) to produce a polymer electrolyte, thereby solving the above problem.

  Hereinafter, the manufacturing process of the polymer electrolyte membrane of the present invention will be described first for each stage, and components used in each manufacturing stage will be described in the following description of the polymer electrolyte membrane. However, since the initiator is used in the manufacturing process and does not remain in the final polymer electrolyte membrane, it will be described when explaining the manufacturing process of the present invention.

  First, a curable oligomer having a low molecular weight and in a liquid state at room temperature and a nano-sized proton conductive polymer are uniformly mixed to produce a dispersion (S1).

  In the mixing step (S1) of the curable oligomer and the nano-sized proton conductive polymer, the mixing ratio of the curable oligomer and the nano-sized proton conductive polymer is preferably 10 to 90:10 to 90 mass ratio, A ratio of thru 70:30 to 70 is more preferable.

  The proton conductive polymer can be used in a solid form, but generally, it is preferably used in a liquid state by adding to a solvent. Examples of the solvent include ethanol, isopropyl alcohol, ethyl alcohol, and n-propyl alcohol. , Alcohols such as butyl alcohol, N-methyl-2-pyrrolidinone (NMP), dimethylformamide (DMF), dimethylacetamide (DMA), tetrahydrofuran (tetrahydrofuran), THF Dimethyl sulfoxide (DMSO), acetone, methyl ethyl ketone (methyl ethyl ketone) ne; MEK), tetramethylurea, trimethyl phosphate, butyrolactone, isophorone, carbitol acetate, methyl isobutyl ketone, N-butyl acetate, cyclohexanone, diacetone alcohol, diisobutyl ketone, ethyl acetoacetate, glycol ether, propylene carbonate, ethylene Carbonate, dimethyl carbonate, diethyl carbonate or deionized water and mixtures thereof can be used. More preferably, a mixture of water and 2-propanol can be used.

  A reaction initiator is added to the dispersion, and an electron beam or ultraviolet ray is irradiated to induce a crosslinking reaction of the oligomer (S2) to produce a polymer electrolyte.

Examples of the initiator include benzoyl peroxide, acetyl peroxide, dilauryl peroxide, potassium persulfate, alkyl peroxides such as di-t-butyl peroxide and chlorobenzophenone, cumene hydroperoxide, peresters such as t-butyl perbenzoate, Or an azo compound is mentioned. As the azo compound, RN = NR ′ (where R and R ′ are CH ₃ , (CH ₃ ) ₃ C, C ₆ H ₅ (CH ₃ CH), (C ₆ H ₅ ) C, (CH _{3 2} (CN) C.).

  The content of the reaction initiator added to the dispersion is preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the curable oligomer. When the amount of the initiator used is less than 0.1 parts by weight with respect to 100 parts by weight of the curable oligomer, the degree of crosslinking is low, and when it exceeds 5 parts by weight, it is physically disturbed by the crosslinking rather than as an impurity. Since the possibility of existing increases, it is not preferable. The initiator plays a role in initiating the curing of the oligomer, and after the production process is completed, a polymer electrolyte membrane is produced, and after the catalyst layer is bound, it is washed in the sulfuric acid treatment process, Preferably it does not remain.

  At the same time, it is preferable that the electron beam or ultraviolet irradiation process is performed under conditions of a dry room or a clean room at room temperature. The electron beam or ultraviolet ray irradiation step is performed by irradiating an electron beam or ultraviolet ray of about 1 kV for about 10 seconds.

  In the case of the polyelectrolyte produced in the above process, the conductivity of the electrolyte matrix is positive due to percolation by physical contact of positive conductive nanoparticles added in a composition of 50% by mass. Since the polymer electrolyte membrane can be manufactured by performing irradiation with an electron beam and ultraviolet rays for several seconds, the matrix constituting the polymer electrolyte membrane is formed on the electrode support surface. Can be coated while being formed at a high speed, so that the mass productivity of the membrane electrode assembly for fuel cells is improved. At the same time, the polymer electrolyte membrane of the present invention can be produced with a thin thickness of 30 to 80 μm.

  The polymer electrolyte membrane of the present invention includes a polymer matrix in which a curable oligomer is crosslinked, and a nano-sized proton conductive polymer present in the polymer matrix.

As the curable oligomer that is a component constituting the polymer matrix, one having one unsaturated functional group at both ends of the chain can be used. A typical example is polyethylene glycol diacrylate represented by the following chemical formula 1 in which the number of ethylene oxide groups (—CH ₂ CH ₂ O—) in the oligomer is 3 to 14.

  The molecular weight of the curable oligomer can be adjusted by the physical properties of the target polymer electrolyte membrane. That is, when the flexibility of the polymer electrolyte membrane is required, it is preferable to use an oligomer having 9 or more ethylene oxide groups (that is, having a molecular weight of 500 or more), and excellent strength is required. In some cases it is preferred to use oligomers having a lower molecular weight.

[Chemical 1]
CR ₁ R ₂ = CR ₃ COO (CH ₂ CH ₂ O) pCOCH = CR ₁ R ₂

In Formula 1, R ₁ , R ₂ , and R ₃ are a hydrogen atom or an alkyl chain having 1 to 12 carbon atoms, and R _{1 to} R ₃ may be the same as or different from each other. , P is an integer from 3 to 14.

  In the state where the curable oligomer is uniformly mixed with the proton conductive polymer nanoparticles, a polymer matrix having a network structure is formed by a crosslinking reaction, so that the dimensional stability of the polymer electrolyte membrane is effectively improved. And the passage of reactants can be suppressed.

  The content of the curable oligomer is preferably 10 to 90% by mass, more preferably 20 to 80% by mass with respect to the total mass of the polymer electrolyte membrane so as to suit the purpose of use. In order to increase conductivity, 30 to 70% by mass is most preferable. At this time, if the content of the curable oligomer is 10% by mass, the degree of cross-linking is reduced due to the dilution effect of the oligomer, so that a network structure cannot be formed, so that dimensional stability is maintained when manufacturing into a thin film. However, if it exceeds 90% by mass, the ion conductivity of the polymer electrolyte membrane may be reduced.

  As the nano-sized proton conductive polymer existing in the polymer matrix, fluorine-based, non-fluorine-based, and hydrocarbon-based proton conductive polymers can be used.

  For the fluorine-based proton conductive polymer, an ion exchange resin having a cation exchange group such as a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a phosphonic acid group, or a derivative thereof in the side chain can be used. The ion exchange resin preferably has an ion exchange ratio of 3 to 33. In this specification, the ion exchange ratio refers to a value defined by the number of carbon and cation exchange groups in the polymer main chain. Further, when such an ion exchange ratio is converted into an equivalent weight (EW) defined as the weight of the acidic polymer required for neutralizing one equivalent of base (NaOH), it is about 500 to 2,000. It corresponds to the equivalent weight. This equivalent weight can adjust the conductivity of hydrogen ions, and if the equivalent weight is excessively large, the electrical resistance increases accordingly, but if it is too small, the mechanical properties decrease. It is preferable to adjust within an appropriate range.

  Further, H can be substituted with Na, K, Li, Cs, or tetrabutylammonium in the hydrogen ion conductive group of such a fluorine-based proton conductive polymer. When replacing H with Na by an ion exchange group at the end of the side chain, replace with NaOH, when using tetrabutylammonium, replace with tetrabutylammonium hydroxide, and K, Li or Cs is also a suitable compound Can be used to substitute. Since this replacement method is widely known in the art, a detailed description thereof will be omitted in this specification.

  Examples of the fluorine-based proton conductive polymer include a perfluoro-based polymer or a fluoroether-based polymer, and specific examples thereof include poly (perfluorosulfonate) of the following chemical formula 2 (trade name: Nafion) (Registered trademark) (sold by E.I. Dupont), Aciplex (Asahi Kasei Chemical), Flemion (Asahi Glass) and Fumion (fumatech), etc.), a fluorocarbon vinyl ether of the following chemical formula 3 or a chemical formula 4 of the following chemical formula 4 Fluorinated vinyl ethers may be mentioned. Or U.S. Pat. Nos. 4,330,654, 4,358,545, 4,417,969, 4,610,762, 4,433,082, and 5,094,995. No. 5,596,676, and 4,940,525 can be used.

(In Formula 2, X is H, Li, Na, K, Cs or TBA (tetrabutylammonium) or NR1R2R3R4, and R1, R2, R3, and R4 are independently H, CH3, or C2H5. And m is 1 or more, n is 2, x is about 5 to 13.5, and y is 1,000 or more.)

(In Formula 3, Rf is fluorine or a C _{1 to} C ₁₀ perfluoroalkyl radical, Y is fluorine or a trifluoromethyl radical, n is an integer of 1 to 3, M is fluorine, The hydroxyl radical, amino radical, and -OMe (Me is an alkali metal radical and a quaternary ammonium radical) are selected.)

(In Formula 4, k is 0 or 1, and l is an integer of 3 to 5.)

  The poly (perfluorosulfonate) shown in Formula 2 has a micellar structure when the sulfonic acid group at the chain end is hydrated, which provides a passage for hydrogen ion migration and is typical. It behaves like an aqueous acid.

  The non-fluorine proton conducting polymer includes benzimidazole polymer, polyimide polymer, polyetherimide polymer, polyphenylene sulfide polymer, polysulfone polymer, polyethersulfone polymer, polyether. Examples thereof include ketone polymers, polyether-ether ketone polymers, polyphenylquinoxaline polymers, polyether polymers, polyphenylene oxide polymers, and polyphosphazene polymers. Specific examples of the non-fluorine proton conducting polymer include polybenzimidazole, polyimide, polysulfone, polysulfone derivatives, sulfonated poly (ether ether ketone) (s-PEEK: s-PEEK). ), Polyphenylene oxide, polyphenylene sulfide, and polyphosphazene.

  Further, as the hydrocarbon proton conductive polymer, a form in which a polystyrene sulfonic acid polymer is grafted to a monomer such as polyethylene, polypropylene, fluoroethylene polymer, ethylene tetrafluoroethylene copolymer, or the like is used. Can do.

  In the present invention, the proton conductive polymer is preferably a perfluoro polymer, a polybenzimidazole polymer or a polysulfone polymer, and most preferably poly (perfluorosulfonate).

  In the present invention, the proton conductive polymer can be used in the form of a single substance or a mixture, and the amount used thereof is 10 to 90 mass relative to the mass of the entire polymer electrolyte membrane so as to suit the purpose of use. % Is preferable, 20 to 80 mass% is more preferable, and 30 to 70 mass% is most preferable.

  In the polymer electrolyte membrane according to the present invention, the proton-conducting polymer nanoparticles are solid-state or non-fluorine-based, hydrocarbon-based, or fluorine-based cation exchange resin particles dispersed in deionized water and an alcohol-based solvent. Can be used, preferably having a particle size of 10 to 200 nm, most preferably 10 to 100 nm.

  At this time, if the content of the fluorine-based cation exchange resin particles is too small, a decrease in the ionic conductivity of the polymer electrolyte membrane occurs, and if the content is excessively large, the mechanical strength decreases and the high The separation performance of the fuel gas (and / or liquid) of the molecular electrolyte membrane may be reduced.

  In addition, one or more polymers selected from sulfonated polyimide, polysulfone, poly (ether ether ketone), polybenzimidazole (PBI), and the like can be used in the form of particles.

Moreover, a block copolymer can also be used as proton conductive polymer nanoparticles. In the block copolymer, a hydrophilic monomer and a hydrophobic monomer are used in an S-block and an F-block, and these are copolymerized to form a biblock (SF form). ) Or triblock (SFS or FSF form) block copolymer nanoparticles are synthesized, and the copolymer is obtained by sulfonation. Since the block copolymer is manufactured so that the properties of the outer blocks are the same, the manufactured copolymer is wound together with the chain, and the polymer chain is looped to form nanoparticles. Is to be manufactured. Examples of the hydrophilic monomer include polyethylene oxide having a —CH ₂ CH ₂ O— unit, polypropylene oxide having a —CH ₂ C (CH ₃ ) CHO— unit, —CH ₂ C (ph) H— (where ph Polystyrene sulfonic acid (PSSA) having a phenyl group) unit can be used, and as the hydrophobic monomer, polyvinylpyrrolidone having a —CH ₂ C (C ₅ H ₄ N) H unit, —COCRHNH-unit Polyacetoamines having the following can be used:

  The polymer electrolyte membrane of the present invention may further contain organic and inorganic additives. The organic and inorganic additives are fine inorganic powders in the form of a fine powder, and when the polymer electrolyte membrane operates at a temperature of 100 ° C. or higher, moisture is evaporated and hydrogen ion conductivity is reduced. Can be prevented.

  The organic and inorganic additives are dispersed in the polymer electrolyte membrane in the form of a powder having a diameter of about 10 to 500 nm, thereby increasing hydrogen ion migration sites and / or moisturizing sites. The addition amount of the organic and inorganic additives is preferably 0.5 to 3 parts by weight with respect to 100 parts by weight of the entire polymer electrolyte membrane. If the amount of organic and inorganic additives added is less than 0.5 parts by weight with respect to 100 parts by weight of the entire polymer electrolyte membrane, the effect is insignificant. If it exceeds 3 parts by weight, the mechanical strength is reduced. This is not preferable.

Examples of the inorganic ion conductor, that is, hydrogen ion conductor, include phosphotungstic acid, silicon tungstic acid, zirconium hydrogen phosphate, α-Zr (O _a1 PCH _a2 OH) _a (O _b1 PC _b2 H _b4 SO _b5 H) _b · nH ₂ O, ν-Zr (PO _a1 ) (H _a2 PO _a3 ) _a (HO _b1 PC _b2 H _b3 SO _b4 H) _b · nH ₂ O, Zr (O _a1 PC _a2 H _a3 ) _a Y _b , Zr (O _a1 PCH _a2 OH) _a Y _b · nH ₂ O, α-Zr (O _a1 PC _a2 H _a3 SO _a4 H) _a · nH ₂ O, α-Zr (O _a1 POH) · H ₂ O, ( One or more mixtures selected from the group consisting of P ₂ O ₅ ) _a (ZrO ₂ ) _b glass and P ₂ O ₅ —ZrO ₂ —SiO ₂ glass are preferred. In the above formula, a1, a2, a3, a4, a, b1, b2, b3, b4, b5, and b are the same or independently an integer of 0 to 14, and n is 0 to An integer of 50.

  Alternatively, the hydrogen ion conductor can be used by being supported on a support by a process known in the art. At this time, the use of the support can be expected to improve the mechanical properties of the cation exchange resin and inorganic additive of the hydrogen ion conductor.

  Examples of the support include silica (fumed silica, trade name: Aerosil, Cabo-sil, etc.), clay, alumina, mica or zeolite (trade names: SAPO-5, XSM-5, AIPO-5, VPI-5, and MCM-41 etc.) can be used. Examples of the clay include montmorillonite, saponite, hectorite, laponite, and tetrasilicin mica.

  The fuel cell system including the polymer electrolyte membrane of the present invention includes at least one electricity generation unit, a fuel supply unit, and an oxidant supply unit.

  The electricity generating unit includes a polymer electrolyte membrane, cathode and anode electrodes and separators (also referred to as bipolar plates) existing on both sides of the polymer electrolyte membrane, and the electricity is generated through an electrochemical reaction between the fuel and the oxidant. It plays a role to generate.

  The cathode electrode and the anode electrode include an electrode base material and a catalyst layer.

  The catalyst layer comprises platinum, ruthenium, osmium, platinum-ruthenium alloy, platinum-osmium alloy, platinum-palladium alloy, and platinum-M alloy (M is Ga, Ti, V, Cr, Mn, Fe, Co, Ni It is preferable to include one or more catalysts selected from the group consisting of Cu, Zn, Sn, Mo, W, Rh, and one or more transition metals selected from the group consisting of combinations thereof. As described above, the same material may be used for the anode electrode and the cathode electrode. However, in the direct oxidation fuel cell, a catalyst poisoning phenomenon caused by CO generated during the anode electrode reaction occurs, so that this can be prevented. A platinum-ruthenium alloy catalyst is more preferable as the anode electrode catalyst. More preferably, Pt, Pt / Ru, Pt / W, Pt / Ni, Pt / Sn, Pt / Mo, Pt / Pd, Pt / Fe, Pt / Cr, Pt / Co, Pt / Ru / W, Pt / One or more selected from the group consisting of Ru / Mo, Pt / Ru / V, Pt / Fe / Co, Pt / Ru / Rh / Ni, and Pt / Ru / Sn / W can be used. .

  Moreover, such a metal catalyst can be used for the metal catalyst itself (black), or can be used by being supported on a carrier. As this carrier, carbon such as acetylene black, denka black, activated carbon, ketjen black, graphite can be used, or inorganic fine particles such as alumina, silica, titania, zirconia, etc. can be used. In general, carbon is widely used.

  The catalyst layer is formed by applying a composition containing the catalyst, a binder, and a solvent to the electrode substrate. The mixing ratio of the catalyst, binder, and solvent may be appropriately adjusted depending on the desired purpose.

  As the binder, those that also serve as ionomers can be used. Examples thereof include fluoropolymers such as perfluorosulfonate, polyamide polymers, polyether polymers, benzimidazole polymers, and polyimide polymers. , Polyetherimide polymer, polyphenylene sulfide polymer, polysulfone polymer, polyethersulfone polymer, polyetherketone polymer, polyether-etherketone polymer, polyphenylquinoxaline polymer, etc. One or more hydrogen ion conductive polymers can be used. In the hydrogen ion conductive polymer, H can be replaced with Na, K, Li, Cs, or tetrabutylammonium at the ion exchange group at the end of the side chain. When replacing H with Na by the ion exchange group at the end of the side chain, when replacing the catalyst composition with NaOH, when using tetrabutylammonium, replace with tetrabutylammonium hydroxide, Li or Cs can also be substituted using a suitable compound. Since this replacement method is widely known in the art, a detailed description thereof will be omitted in this specification.

  The binder resin can be used in the form of a single substance or a mixture, and can also be used together with a non-conductive polymer for the purpose of selectively improving the adhesive force with the polymer electrolyte membrane. . The amount used is preferably adjusted to suit the purpose of use.

  Examples of the non-conductive polymer include polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer ethylene / tetrafluoroethylene, and trifluoroethylene chloride-ethylene copolymer. One or more selected from the group consisting of a coalescence, polyvinylidene fluoride, and a copolymer of polyvinylidene fluoride-hexafluoropropylene can be used.

  As the solvent, water, alcohol such as methanol, ethanol, isopropyl alcohol, N-methylpyrrolidone, dimethylacetamide, dimethylsulfoxide, tetrahydrofuran, acetone, or a mixture thereof can be used.

  The electrode base material plays a role of supporting the electrode, and diffuses fuel and oxidant in the catalyst layer so that the fuel and oxidant can easily approach the catalyst layer. A conductive base material is used as the electrode base material, and typical examples thereof include carbon paper, carbon cloth, carbon felt, or metal cloth (a porous film or polymer fiber made of a metal cloth in a fiber state). In this case, a metal film formed on the surface of the fabric formed in (1) may be used, but the present invention is not limited to this.

  In addition, it is preferable to use the electrode base material that has been subjected to a water repellent treatment with a fluorine-based resin, since it is possible to prevent a reduction in reactant diffusion efficiency due to water generated when the fuel cell is driven. Examples of the fluororesin include polyvinylidene fluoride, polytetrafluoroethylene, fluorinated ethylene propylene, polytrifluoroethylene chloride, and fluoroethylene polymer.

  Further, it may further include a microporous layer for enhancing the reactant diffusion effect in the electrode substrate. This microporous layer is generally a conductive powder having a small particle size, such as carbon powder, carbon black, acetylene black, activated carbon, carbon fiber, fullerene, carbon nanotube, carbon nanowire, carbon nanohorn or carbon nanoring. Can be included. The microporous layer is manufactured by coating the electrode substrate with a composition containing conductive powder, a binder resin, and a solvent. As the binder resin, polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl alcohol, cellulose acetate and the like are preferably used, and as the solvent, ethanol, isopropyl alcohol, n-propyl alcohol, alcohol such as butyl alcohol, water, Dimethylacetamide, dimethylsulfoxide, N-methylpyrrolidone and the like are preferably used. The coating process may be a screen printing method, a spray coating method, or a coating method using a doctor blade depending on the viscosity of the composition, but is not limited thereto.

  The fuel supply unit serves to supply fuel to the electricity generation unit, and the oxidant supply unit serves to supply an oxidant such as oxygen or air to the electricity generation unit. In the present invention, the fuel means a hydrocarbon fuel such as methanol, ethanol, propanol, butanol or natural gas in a gas or liquid state. Of course, hydrogen can also be used.

  The schematic structure of the fuel cell system of the present invention is shown in FIG. 2 and will be described in more detail with reference to FIG. FIG. 2 shows a system for supplying an oxidant to an electricity generator using a pump. However, the fuel cell system of the present invention is not limited to such a structure, and the pump is not used. Naturally, it can be used for a fuel cell system structure for supplying an oxidant in a diffusion manner.

  The fuel cell system 1 according to the present invention includes at least one electricity generation unit 3 that generates electric energy through a fuel oxidation reaction and an oxidant reduction reaction, a fuel supply unit 5 that supplies the fuel, and an oxidant that is used as the electricity. An oxidant supply unit 7 that supplies the generation unit 3 is included.

  The fuel supply unit 5 for supplying the fuel may include a fuel tank 9 for storing fuel and a fuel pump 11 connected to the fuel tank 9. The fuel pump 11 functions to discharge the fuel stored in the fuel tank 9 with a predetermined pumping force.

  The oxidant supply unit 7 that supplies the oxidant to the electricity generating unit 3 includes at least one oxidant pump 13 that sucks the oxidant with a predetermined pumping force.

  The electricity generating unit 3 includes an electrode assembly 17 that oxidizes and reduces a fuel and an oxidant, and separators 19 and 19 ′ for supplying fuel and an oxidant to both sides of the electrode assembly. At least one such electricity generator 17 gathers to form a stack 15.

  Hereinafter, preferred examples and comparative examples of the present invention will be described. However, the following embodiment is only a preferred embodiment of the present invention, and the present invention is not limited to the following embodiment.

Example 1
Commercially available 20% by weight Nafion® / H ₂ O (EI Dupont de Nemour, EW = 1,100: Formula 2, X = H, m is 1, n is 2, (x is about 5 to 13.5, and y is 1,000 or more) 60 g of a proton conductive polymer nanoparticle dispersion of 100 nm was added to 0.82 g of NaOH and 9 g of polyethylene glycol diacrylate (Aldrich, MW = 742, chemical formula 1, p = 14) After mechanically stirring the oligomer with the oligomer for 6 hours at room temperature, 0.9 g of chlorobenzophenone was added to the mixture, and the mixture was additionally stirred for 5 minutes and coated on the glass plate. Then, a polymer electrolyte membrane was produced by irradiating with 1 kV ultraviolet rays.

5% by weight of Nafion® / H ₂ O / 2-propanol solution, 1M tetrabutylammonium hydroxide / methanol dipropylene glycol, and deionized water were added to Pt-Ru black (referred to as a catalyst not supported on a carrier). , Johnson Matthey, HiSpec 6000) and Pt black (Johnson Matthey, HiSpec 1000) particles were mixed to produce a catalyst slurry, followed by screen printing on a Teflon (registered trademark) film and drying to prepare the catalyst layer. Each of the cathode and anode was placed on the polymer electrolyte membrane and then thermocompression bonded at 200 ° C. under a pressure of 500 psi for 3 minutes so that the loading amount was 4 mg / cm ² on the polymer electrolyte membrane. The electrode was bound. At this time, the Nafion (registered trademark) content in the catalyst layer was adjusted to 15% by mass relative to the catalyst mass. The 3-layer membrane electrode assembly was combined with a 31BC electrode substrate (diffusion layer) manufactured by SGL Carbon to produce a 5-layer electrode assembly (MEA).

  The manufactured MEA is inserted between glass fiber gaskets coated with polytetrafluoroethylene, and then inserted into two separators each having a gas flow channel and a cooling channel having a certain shape, and then copper. A unit cell is manufactured by pressing between end plates, and methanol crossover current is measured in a state in which methanol and elementary substances are introduced. The output change was measured.

(Comparative Example 1)
A commercial Nafion (registered trademark) 115 membrane (125 μm) was treated with 3% hydrogen peroxide and 0.5 M aqueous sulfuric acid at 100 ° C. for 1 hour, and then washed with deionized water at 100 ° C. for 1 hour. A molecular electrolyte membrane was manufactured.

(Comparative Example 2)
A commercially available Gore-Select membrane (25 μm) was pretreated by the same method as in Comparative Example 1 to produce a polymer electrolyte membrane.

(Comparative Example 3)
While stirring 100 g of a 5% by mass commercial Nafion® / H ₂ O / 2-propanol (Solution Technology Inc., EW = 1,100) solution at room temperature for 48 hours, the solvent was increased. After preparing the Nafion® gel, 95 g of dimethylacetamide was added to prepare an approximately 5% by weight Nafion® / dimethylacetamide solution. This solution was preheated in a 60 ° C. water bath for 24 hours to evaporate the remaining water.

  Separately, 5 g of polyvinylidene fluoride (Elf Atochem America, Inc., Kynar Flex 761) was dissolved in 95 g of dimethylacetamide to prepare a 5 mass% polyvinylidene fluoride / dimethylacetamide solution. 20 g of the polyvinylidene fluoride / dimethylacetamide solution was mixed with 50 g of the 5% by weight Nafion® / dimethylacetamide solution prepared.

  1 g of polyethylene glycol diacrylate (Aldrich, MW = 742) was added to the mixture prepared as described above, and the mixture was vigorously stirred at 50 ° C. for 10 minutes. Thereafter, 0.03 g of benzoyl peroxide was added to the mixture, and the mixture was vigorously stirred for 10 minutes and then applied onto the polytetrafluoroethylene surface using a doctor blade.

  The film was heated in an oven maintained at about 100 ° C. for 12 hours to produce a composite polymer electrolyte membrane having a thickness of 30 μm.

  The conductivity of the ions of the electrolyte membranes manufactured according to Example 1 and Comparative Examples 1 to 3 was obtained through impedance measurement using temperature and relative humidity changes using a conductivity measuring cell manufactured by BekkTech, and the result. Is shown in Table 1 below.

The methanol permeability of the electrolyte membranes manufactured according to Example 1 and Comparative Examples 1 to 3 was determined by placing the electrolyte membrane sample in the center of the two-compartment diffusion cell and mixing 15% by mass of methanol / deionized water at both ends. When liquid and deionized water were circulated, the concentration of methanol that permeated the electrolyte membrane was measured by the change in refractive index. The change in the area of the electrolyte membrane indicates the increase rate of the area increased by swelling the 5 × 5 cm ² electrolyte membrane with moisture at room temperature. The results are shown in Table 1 below.

As shown in Table 1, when the polymer electrolyte membrane of Example 1 was compared with the pure Nafion (registered trademark) membrane of Comparative Example 1, the ionic conductivity decreased, but the mechanical strength was high. Therefore, the conductivity (S / cm ² ) of the electrolyte membrane depending on the thickness was improved as compared with Comparative Example 1. In addition, compared with the pure Nafion (registered trademark) membrane of Comparative Example 1, it was confirmed that the dimensional stability and the barrier property against methanol were excellent, and the unit cell output density was comparable under the same conditions when operated at 70 ° C. Results were obtained. At the same time, in the polymer electrolyte membrane of Example 1, the oligomer was cross-linked by ultraviolet irradiation, and the formation of the electrolyte matrix could be carried out within a few seconds, so that the mass productivity was improved.

  In addition, the polymer electrolyte membrane of Example 1 shows comparable dimensional stability as compared with Comparative Example 2 of the reinforced composite membrane, and has a lower methanol permeability than Comparative Example 2 in which excessive methanol permeation occurs. It can be seen that the unit cell output density is much better when operated at 70 ° C.

  At the same time, the polymer electrolyte membrane of Example 1 is superior in dimensional stability compared to Comparative Example 3, has a low methanol permeability, and has a much better unit cell output density when operated at 70 ° C. I understand that.

  3A and 3B are SEM photographs showing cross sections of the polymer electrolyte membranes of Example 1 and Comparative Example 3, respectively. As shown in FIGS. 3A and 3B, when the cross section of the polymer electrolyte membrane according to Example 1 is seen, nano-sized proton conductive polymer nanoparticles having a uniform particle size distribution as compared with Comparative Example 1 It can be seen that it has a much more uniform cross-sectional shape.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to these embodiments, and various modifications may be made within the scope of the claims, the detailed description of the invention and the attached drawings. This is also within the scope of the present invention.

It is the figure which showed roughly the process of manufacturing the polymer electrolyte membrane of this invention. It is the figure which showed the fuel cell system of this invention roughly. 4 is SEM photographs showing cross sections of polymer electrolyte membranes according to Example 1 and Comparative Example 3, respectively. 4 is SEM photographs showing cross sections of polymer electrolyte membranes according to Example 1 and Comparative Example 3, respectively.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell system 3, 17 Electricity generation part 5 Fuel supply part 7 Oxidant supply part 9 Fuel tank 11 Fuel pump 13 Oxidant pump 15 Stack 19, 19 'Separator

Claims (32)

A polymer matrix cross-linked with a curable oligomer; and nano-sized proton conducting polymer nanoparticles present in the polymer matrix;
A fuel cell polymer electrolyte membrane.   The polymer electrolyte membrane for a fuel cell according to claim 1, wherein the curable oligomer is an oligomer having one unsaturated functional group at both ends of the chain. The polymer electrolyte membrane for a fuel cell according to claim 2, wherein the curable oligomer is an oligomer of the following chemical formula 1 having 3 to 14 ethylene oxides.
[Chemical 1]
CR ₁ R ₂ = CR ₃ COO (CH ₂ CH ₂ O) pCOCH = CR ₁ R ₂
(In Formula 1, R ₁ , R ₂ , and R ₃ are a hydrogen atom or an alkyl chain having 1 to 12 carbon atoms, and at this time, R _{1 to} R ₃ may be the same as or different from each other. And p is an integer from 3 to 14.)   The polymer electrolyte membrane for a fuel cell according to claim 1, wherein the content of the curable oligomer is 10 to 90 mass% with respect to the mass of the entire polymer electrolyte membrane.   The polymer electrolyte membrane for a fuel cell according to claim 4, wherein the content of the curable oligomer is 20 to 80% by mass with respect to the mass of the whole polymer electrolyte membrane.   The polymer electrolyte membrane for a fuel cell according to claim 5, wherein the content of the curable oligomer is 30 to 70 mass% with respect to the mass of the entire polymer electrolyte membrane.   The polymer electrolyte membrane for a fuel cell according to claim 1, wherein the proton conductive polymer is selected from the group consisting of fluorine-based, non-fluorine-based, and hydrocarbon-based proton conductive polymer nanoparticles.   The fluorine-based proton conductive polymer has a cation exchange group selected from the group consisting of a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a phosphonic acid group, and derivatives thereof in a side chain. The polymer electrolyte membrane for fuel cells as described.   The polymer electrolyte membrane for a fuel cell according to claim 7, wherein the fluorine-based proton conductive polymer has an ion exchange ratio of 3 to 33 and an equivalent weight of 500 to 2,000.   The polymer electrolyte membrane for a fuel cell according to claim 1, wherein the proton conductive polymer is 10 to 90 mass% with respect to the mass of the entire polymer electrolyte membrane.   The polymer electrolyte membrane for a fuel cell according to claim 10, wherein the proton conductive polymer is 20 to 80% by mass with respect to the mass of the entire polymer electrolyte membrane.   The polymer electrolyte membrane for a fuel cell according to claim 11, wherein the proton conductive polymer is 30 to 70 mass% with respect to the mass of the entire polymer electrolyte membrane.   The proton conductive polymer is produced by copolymerizing a hydrophilic monomer and a hydrophobic monomer to produce a biblock or triblock copolymer, and sulfonating the copolymer. The polymer electrolyte membrane for fuel cells according to claim 1.   The polymer electrolyte membrane for a fuel cell according to claim 1, wherein the polymer electrolyte membrane further comprises organic and inorganic additives.   The polymer electrolyte membrane for a fuel cell according to claim 14, wherein the organic and inorganic additives are hydrophilic inorganic ion conductors. The inorganic ion conductor includes phosphotungstic acid, silicon tungstic acid, zirconium hydrogen phosphate, α-Zr (O _a1 PCH _a2 OH) _a (O _b1 PC _b2 H _b4 SO _b5 H) b · nH ₂ O (where , A1, a2, a, b1, b2, b4, b5, and b are the same or independently an integer from 0 to 14, and n is an integer from 0 to 50), ν−. Zr (PO _a1 ) (H _a2 PO _a3 ) _a (HO _b1 PC _b2 H _b3 SO _b4 H) _b · nH ₂ O (where a1, a2, a3, a, b1, b2, b3, b4, b5, And b are the same or independently an integer of 0 to 14, and n is an integer of 0 to 50.), Zr (O _a1 PC _a2 H _a3 ) _a Y _b (where a1 , A2, a3, a, and b are Are the same or independently an integer of 0 to 14), Zr (O _a1 PCH _a2 OH) _a Y _b · nH ₂ O (where a1, a2, a, and b are the same) Or an integer of 0 to 14 and n is an integer of 0 to 50), α-Zr (O _a1 PC _{a2 Ha a3} SO _a4 H) _a · nH ₂ O (where, a1, a2, a3, a4, and a are the same or independently an integer of 0 to 14 and n is an integer of 0 to 50), α-Zr (O _a1 POH). H ₂ O (where a1 is an integer from 0 to 14), (P ₂ O ₅ ) _a (ZrO ₂ ) _b glass (where a and b are integers from 01 to 14), and one and is selected from the group consisting of _{P 2 O} 5 -ZrO 2 -SiO 2 glass One or more of those selected from the group consisting of a mixture, the polymer membrane for a fuel cell according to claim 15. An anode electrode and a cathode electrode positioned opposite to each other, and a polymer electrolyte membrane positioned between the anode electrode and the cathode electrode. At least one electricity generating part that generates electricity through a chemical reaction;
A fuel supply unit that supplies fuel to the electricity generation unit; and an oxidant supply unit that supplies oxidant to the electricity generation unit;
The polymer electrolyte membrane is
A fuel cell system comprising: a polymer matrix in which a curable oligomer is crosslinked; and a nano-sized proton conducting polymer present in the polymer matrix.   The fuel cell system according to claim 17, wherein the curable oligomer is an oligomer having one unsaturated functional group at both ends of the chain. The fuel cell system according to claim 18, wherein the curable oligomer is an oligomer of the following chemical formula 1 having 3 to 14 ethylene oxides.
[Chemical 1]
CR ₁ R ₂ = CR ₃ COO (CH ₂ CH ₂ O) pCOCH = CR ₁ R ₂
(In Formula 1, R ₁ , R ₂ , and R ₃ are hydrogen atoms or alkyl chains having 1 to 12 carbon atoms, and at this time, R _{1 to} R ₃ are the same or different from each other. And p is an integer from 3 to 14.)   The fuel cell system according to claim 19, wherein the content of the curable oligomer is 10 to 90 mass% with respect to the mass of the whole polymer electrolyte membrane.   21. The fuel cell system according to claim 20, wherein the content of the curable oligomer is 20 to 80% by mass with respect to the mass of the entire polymer electrolyte membrane.   The fuel cell system according to claim 21, wherein the content of the curable oligomer is 30 to 70 mass% with respect to the mass of the entire polymer electrolyte membrane.   The fuel cell system according to claim 19, wherein the proton conductive polymer is formed of a fluorine-based, non-fluorine-based, or hydrocarbon-based proton conductive polymer.   The fluorine-based proton conductive polymer has a cation exchange group selected from the group consisting of a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a phosphonic acid group, and derivatives thereof in the side chain. The fuel cell system according to claim 23.   The fuel cell system according to claim 24, wherein the fluorine-based proton conductive polymer has an ion exchange ratio of 3 to 33 and an equivalent weight of 500 to 2,000.   18. The fuel cell system according to claim 17, wherein the proton conductive polymer is 10 to 90% by mass with respect to the mass of the entire polymer electrolyte membrane.   27. The fuel cell system according to claim 26, wherein the proton conductive polymer is 20 to 80% by mass with respect to the mass of the entire polymer electrolyte membrane.   28. The fuel cell system according to claim 27, wherein the proton conductive polymer is 30 to 70% by mass with respect to the mass of the entire polymer electrolyte membrane.   The proton conductive polymer is produced by copolymerizing a hydrophilic monomer and a hydrophobic monomer to produce a biblock or triblock copolymer, and sulfonating the copolymer. Item 18. The fuel cell system according to Item 17.   The fuel cell system according to claim 17, wherein the polymer electrolyte membrane further includes organic and inorganic additives.   The fuel cell system according to claim 30, wherein the organic and inorganic additives are hydrophilic inorganic ion conductors. The inorganic ion conductor includes phosphotungstic acid, silicon tungstic acid, zirconium hydrogen phosphate, α-Zr (O _a1 PCH _a2 OH) _a (O _b1 PC _b2 H _b4 SO _b5 H) _b · nH ₂ O (where , A1, a2, a, b1, b2, b4, b5, and b are the same or independently an integer from 0 to 14, and n is an integer from 0 to 50), ν−. Zr (PO _a1 ) (H _a2 PO _a3 ) _a (HO _b1 PC _b2 H _b3 SO _b4 H) _b · nH ₂ O (where a1, a2, a3, a, b1, b2, b3, b4, b5, And b are the same or independently an integer of 0 to 14, and n is an integer of 0 to 50.), Zr (O _a1 PC _a2 H _a3 ) _a Y _b (where a1 , A2, a3, a, and b Is identical or mutually integer from 0 to _{14.), Zr (O a1} PCH a2 OH) a Y b · nH 2 O ( where, a1, a2, a, and b are the same Or an integer of 0 to 14 and n is an integer of 0 to 50), α-Zr (O _a1 PC _{a2 Ha a3} SO _a4 H) _a · nH ₂ O (where, a1, a2, a3, a4, and a are the same or independently an integer of 0 to 14 and n is an integer of 0 to 50), α-Zr (O _a1 POH). H ₂ O (where a1 is an integer from 0 to 14), (P ₂ O ₅ ) _a (ZrO ₂ ) _b glass (where a and b are integers from 01 to 14), and _{P 2 O} 5 -ZrO 2 -SiO 2 one and one selected from the group consisting of glass It is those selected from the group consisting of a mixture of above, the fuel cell system according to claim 31.